Bad leakage? that is not even a type of leakage. Every transistor has some type of leakage, that is why ES CPUs in previous gens to SB OC so much higher, because usually they had unlock TDPs. I woudl actually expect the higher binned cards for the same type to have lower ASIC if the leakage is what they say is quality of the silicon.

My ref gigabyte GTX 570 is 89.7%

i don't think ASIC refers to just leakage.
overclockers should want higher as higher leakage transistors usually can work faster, that is why they use them in very critical parts of teh GPU.

So, who's got the lowest ASIC quality? My first 470 reads a massive 36.9%, which sounds about right. It was never a strong overclocker. Default VID of 1.037V can be overclocked to 725/1800 at stock volts or 775/1900 at 1.087V. Nothing too spectacular. Best I've ever gotten it was 850/1900 at I think 1.15V. It wasn't 100% stable and the card alone drew more than 400W in Furmark. (Don't worry I had the AXP on it and it never got above 75°C, worry about the VRMs though.)

My other 470 with a quality of 60.9% is a little better. Default VID is 0.975V. 725/1800 at 0.975V and 775/1900 at 1.037V.